Random tidbits Bdale thinks are worth documenting.
Bdale Garbee
bdale@gag.com
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Thu, 22 Jan 2004
Adventures with DVI
Our new display device, a Panasonic
PT-50LC13
LCD rear-projection HDTV set,
arrived and got turned on only a couple of hours before I left for
LCA 2004
in Adelaide. Ever since returning home, I've been working on how to get the
MythTV
frontend driving it optimally.
I'm pretty happy with the results so far.
After trying lots of combinations, I've ended up with an AGP video card using the nVIDIA FX 5200, driving the TV through the DVI cable that came with the set, at 1280x720 pixels resolution to match the display's native resolution (this is 720P in HDTV terminology). The only trick was figuring out a reasonable Modeline for the X config file:
Modeline "720p" 74.25 1280 1312 1592 1648 720 735 742 757
With that, the display is rock-solid and crisp. As a digitally-oriented kind
of guy, I find the whole concept of "overscan" in televisions mildy offensive,
but the industry is accustomed to not having viewers see to the edge of the
transmitted image... and that's just life. What this means in practical terms
with this display is that only the middle 1210x680 of the total 1280x720 pixels
are actually visible. I'm told that's a completely typical overscan percentage
by the folks who hang out on the MythTV IRC channel.
Two consequences of the overscan that I'll have to figure out eventually are that text in the Linux console framebuffer is clipped off on the left and sort of hard to read (only an issue when something breaks), and the MythTV on-screen display could stand to be shrunk slightly to fit into the visible pixel area better. That's probably tweakable in the setup, but I haven't looked yet.
Now I guess I have to decide whether to play with the HD-2000 card I bought from pchdtv.com first, or start tweaking the video capture and display parameters to optimize picture quality. Since it appears that we might actually be able to watch the Super Bowl in HDTV if I get all of that together in time, I'm pretty sure I know what my wife's vote would be... ;-)